Application Study On The Treatment Of Hybrid Wastewater For Cod Upgrading Of Municipal Wastewater Treatment Plant

According to "Twelfth Five-Year Plan" of Zhejiang Province, Municipal wastewater treatment facilities of Taihu Lake Basin and Qiantang River Basin will execute1A standard by2015. Due to the developed industrial economy of Zhejiang, the majority of municipal wastewater treatment plants contain large amounts of industrial wastewater, the primary task of hybird wastewater for municipal wastewater treatment plants in the upgrading task that is COD. The core of this study is the first phase project upgrading technology program of Jiaxing L wastewater treatment plant (L-WWTP), in this study, a pilot test to the feasibility of the process, the selection of process parameters was carried out and the engineering solution was provided.The original design takes oxidation ditch project as the main treatment process in the first phase project of L-WWTP. Through the study of existing treatment process in quality characteristics of influent and effluent, indicating:wastewater composition is complex and quality has a large fluctuation. Moreover, industrial wastewater is about50percents. The wastewater has some biodegradability and activated sludge can not be significantly inhibited, but biodegradable COD (CODnb) value reached100mg/L, and more than80%of organic molecular weight is less than2500. COD, ammonia, SS, TN, TP and other indicators in effluent can not achieve1A standard, especially COD indicator faces a severe upgrading task.Secondary biological treatment pilot study was carried out in the core of an inverted A2O+MBR technology, the results showed that when influent is pure industrial wastewater and MBR is under optimal operating conditions, the average COD of effluent is132.2mg/L and far less than1A standard. Tests showed that the greater of the proportion of sewage, the better of the treatment effect. According to the actual ratio of the amount of industrial wastewater and domestic sewage in the future, stable operation of research was carried out with the sewage/industrial wastewater=1:1, when the influent COD concentration averaged372mg/L, effluent averaged69mg/L and the removal rate averaged80.1%, but still needed the depth process. Through studying the properties of the mixture MBR, higher concentration of MBR sludge will increase the frequency of membrane cleaning and aeration energy. Regular chemical cleaning on line (about20-30d) can ensure stable operation of the membrane flux. The more Sewage ingredients, the less extracellular polymers (EPS) and soluble microbial products (SMP) content in unit MLVSS, but the better Sludge traits.Depth studies were carried out with ozone and activated carbon treatment process-based biofilter. The results showed that the ozone can change the form of the structure of the material in direct reaction with a short period of time to containing chromophore groups and aromatic compound with a simple structure, but can not completely mineralize them, when the dosage is30mg/L and contact time is1h, MBR effluent COD averages from68mg/L reduced to48mg/L, COD indicator meets1A standard of "Cities Sewage treatment plant Pollutant discharge Standard"(GB18918-2002). Ozone oxidizes portion of the macromolecule material into small molecule material. After ozone oxidation, the proportion of organic matter whose molecular weight is less than730increases from30%to54%. Ozonation has a good oxidation on the alkane compounds whose molecular weight are less than500, but a poor oxidation on the various substituent groups of aromatic compounds within the molecular weight range. When the empty bed residence time of activated carbon biofilter is2.5h, COD indicator of effluent can reach1A standard. Revealed, microorganism is mostly concentrated in the surface of the carbon particles and the neighboring big hole by scanning electron microscopy and transmission electron microscopy, but can not enter the microporous.According to the pilot study results, an inverted A2O/MBR+activated carbon biofilter technology was carried out as the core of COD upgrading process. The use of ozonation as an advanced treatment process results in the direct operating running costs to0.68yuan/ton of water, so that the main function of rehabilitation programs set ozone oxidation process to disinfect the main cast as an emergency fluctuations in the effluent COD plus. Thus, the main function of ozonation process in the transformation program was set to disinfect, and as an emergency dosing when effluent COD fluctuates.